QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 559 SYNCHRONOUS BOOST CONVERTER WITH OUTPUT DISCONNECT LTC3429 DESCRIPTION Demonstration circuit 559 is a high efficiency synchro- A switching frequency of 500KHz allows up to 95% effi- nous boost DC/DC converter with output disconnect, ciency with a tiny solution footprint. Typical applications inrush current limiting and soft-start functions featuring include MP3 players, GPS receivers, digital cameras, the LTC3429. The board is capable of supplying 90mA PDAs, LCD bias supplies and wireless handsets. from a single AA cell input or 250mA from a 2-cell input Design files for this circuit board are available. Call with a 3.3V output. The input range is from 1V to 3.3V. the LTC factory. DC559 version A uses the LTC3429 version B uses the LTC3429B. The LTC3429 shifts automatically to power saving Burst Mode operation at light loads whereas the LTC3429B operates at a fixed frequency for all loads with minimum output voltage ripple. Table 1. Performance Summary PARAMETER CONDITION VALUE Maximum Load Current, Min Vout = 3.3V, Vin = 1.0V 90mA Maximum Load Current, Min Vout = 3.3V, Vin = 2.0V 250mA Switching Frequency, Typ 500KHz Efficiency, Typ Vout = 3.3V, Vin = 2.8V, Iout = 100mA 95% Output Ripple, Typ Vout = 3.3V, V = 1.5V, I = 100mA (20MHz BW) 20mV IN OUT PP QUICK START PROCEDURE Demonstration circuit 559 is easy to set up to evaluate 1. Place the jumper in the following position: the performance of the LTC3429. Refer to Figure 1 for JP1 On proper measurement equipment setup and follow the 2. With power off, connect the input power supply to Vin procedure below: and GND. Connect the load to Vout and GND. Set ini- NOTE: When measuring the input or output voltage rip- tial load = 0A (no load). ple, care must be taken to avoid a long ground lead on 3. Turn on the power at the input. the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across NOTE: Make sure that the input voltage does not ex- the Vin or Vout and GND terminals. See Figure 2 for ceed 4.4V. proper scope probe technique. 1 GND VIN QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 559 SYNCHRONOUS BOOST CONVERTER WITH OUTPUT DISCONNECT 4. Check for the output voltage. Vout should be NOTE: If there is no output, temporarily disconnect the 3.3V0.1V. load to make sure that the load is not set too high. The available output current depends on the input 5. Once the proper output voltage is established, adjust voltage. the load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 2